Mahanine synergistically enhances cytotoxicity of 5-fluorouracil through ROS-mediated activation of PTEN and p53/p73 in colon carcinoma

Mahanine mediated therapeutic inhibition of estrogen receptor-α and CDK4/6 expression, decipher the chemoprevention-signaling cascade in preclinical model of breast cancer

ETHNOPHARMACOLOGICAL RELEVANCE

Mahanine (MH), a naturally occurring carbazole alkaloid, isolated from Ayurvedic medicinal plant Murraya koenigii (L.) Spreng, has been shown to have various pharmacological properties, including its inhibitory activity against different breast cancers (BC) subtypes.

AIM OF THE STUDY

While MH triggers apoptosis in BC cells regardless of subtype, the specific mechanism of MH action is not fully understood. In this study, we show the effect of MH in preventing BC progression by inducing apoptosis in relation to estrogen receptor-α (ERα) and cell cycle regulatory proteins.

MATERIALS AND METHODS

To assess the pharmacological activity in various in vitro and in vivo tests, isolated and pure MH was used. To conclude the study, cutting edged molecular biology techniques including Western blot analysis, enzyme-linked immunosorbent assay (ELISA), molecular simulation study, and other related software analysis were employed.

RESULTS

MH demonstrated dose dependent cell viability against drug sensitive (MCF-7 and MDA-MB-231) and paclitaxel resistant (MCF-7TR and MDA-MB-231TR) BC cells. MH also exhibited synergistic activity with tamoxifen (TAM) against estrogen receptor positive (ER+) BC cells by inhibiting ERα expression in MCF-7 cells and N-Methyl-N-nitrosourea (MNU)-induced mammary tumor in a dose-dependent manner while having no effect on vinculin expression. In addition, MH inhibited cell cycle regulatory genes namely CDK1/CDK4/CDK6/CDC25A and neo-angiogenesis through downregulation of CD31/PECAMs in MCF-7, MDA-MB-231 cells and mammary tumors from MNU-induced rats. MH therapy has been shown to be significantly able to lower the serum leptin level and to be beneficial against the initiation of tumor development in SD rats for up to 12 weeks. Molecular modeling study revealed that MH has antagonized the effectiveness of several types of estrogen those bind to the ERα and has comparable binding efficacy to TAM.

CONCLUSION

Overall, the current investigation showed the ability of MH to modify cell cycle genes especially CDK4 and CDK6 might be responsible for its anticancer activity against different breast cancer subtypes. Additionally, this study will aid in advancing MH translational research to the clinical trial stage.

Synergistic Effects of PI3K Inhibition on Arsenic Trioxide Cytotoxicity in Acute Promyelocytic Leukemia Cells: A New Portrait of Idelalisib as an Adjuvant Therapy

The advent of small-molecule inhibitors targeting the components of oncogenic signaling pathways has revolutionized cancer treatment, where the pharmacological approaches have gone from an era of non-specific chemotherapeutic drugs to the golden age of targeted therapies. In the present study, we evaluated the therapeutic value of an isoform-specific inhibitor of PI3K (Idelalisib) in potentiating the anti-leukemic effects of arsenic trioxide (ATO), an eminent drug used in the treatment of acute promyelocytic leukemia (APL). We found that the abrogation of the PI3K axis profoundly reinforced the anti-leukemic effects of the lower concentrations of ATO, as revealed by the superior reduction in the viability, cell number, and metabolic activity of APL-derived NB4 cells as compared to either agent alone. The cytotoxic effect of Idelalisib in combination with ATO was probably mediated through suppression of c-Myc that was coupled with the elevation in the intracellular level of reactive oxygen species and induction of caspase-3-dependent apoptosis. Notably, our results showed that the suppression of autophagy reinforced the ability of the drugs in eradicating the leukemic cells, suggesting that the compensatory activation of this system may probably overshadow the success of Idelalisib-plus-ATO in APL cells. All in all and given the significant efficacy of Idelalisib against NB4 cells, we proposed the application of this PI3K inhibitor as a foreseeable approach with a safe profile in the treatment of APL.

Guttiferone BL from the Fruits of Allanblackia gabonensis Induces Mitochondrial-Dependent Apoptosis in PA-1 Ovarian Cancer Cells

Despite the recent advancement of treatment strategies, cancer ranks 2^nd among the causes of death globally. Phytochemicals have gained popularity as an alternate therapeutic strategy due to their nontoxic nature. Here, we have investigated the anticancer properties of guttiferone BL (GBL) along with four known compounds previously isolated from Allanblackia gabonensis. The cytotoxicity was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. The study was extended for the assessment of the effect of GBL in PA-1 cells apoptosis induction, cell cycle distribution, and change in mitochondrial membrane potential using flow cytometry, Western blot analysis, and real-time PCR. Among the five tested compounds, GBL displayed significant antiproliferative effects against all tested human cancer cells (IC₅₀ < 10μM). Moreover, GBL exhibited no significant cytotoxicity towards normal ovarian epithelial cell line (IOSE 364) up to 50 μM. GBL induced sub-G₀ cell cycle arrest and significant upregulation of cell cycle regulatory proteins of ovarian cancer cell PA-1. Furthermore, GBL induced its apoptosis as depicted by the accumulation of cells both at the early and late apoptotic phase in Annexin V/PI assay. In addition, it decreased the PA-1 mitochondrial membrane potential and promoted upregulation of caspase-3, caspase-9, and Bax and downregulation of Bcl-2. GBL also showed a dose-dependent inhibition of PA-1 migration. Altogether, this study reveals that guttiferone BL, studied herein for the first time, exhibits efficient antiproliferative activity by the induction of apoptosis through the mitochondrial-dependent pathway. Its investigation as a therapeutic agent against human cancers especially ovarian cancer should be envisaged.

The anticancer activity of carbazole alkaloids

Chemotherapy is the first choice for the majority of cancers, but severe side effects and drug resistance restrict the actual clinical efficacy. Carbazole alkaloids, mainly from the Rutaceae family, possess favorable donor ability, good planarity, rich photophysical properties, and excellent biocompatibility. Carbazole alkaloids could not only intercalate in DNA but could also inhibit telomerase and topoisomerase and regulate protein phosphorylation. Hence, carbazole alkaloids are useful in providing lead hits/candidates for the development of novel anticancer agents. This review summarizes the research progress made regarding the anticancer properties of carbazole alkaloids, covering articles published from January 2010 to June 2021.

A Review of the Anti-Cancer Potential of Murraya koenigii (Curry Tree) and Its Active Constituents

Murraya koenigii (MK) relates to the Rutaceae family and has many health benefits. To date, over eighty-eight carbazole alkaloids along with terpenoids, and other nutrients have been identified from different parts of this plant. This review presents accumulated information regarding the role of MK and its constituents in the prevention/treatment of cancer. Literature survey revealed that MK and its constituents target multiple deranged pathways associated with apoptosis, growth (JAK-STAT, mTOR), and cell cycle in a variety of cancerous cell lines (colon, lung, liver, skin, prostate, breast, etc.) and few animal models. Thus, the present review highlights the anticancer mechanism of MK and its phytoconstituents, and further future perspectives. The ameliorating effects of MK and its phytoconstituents against various cancers warrant its multi-institutional clinical trials as soon as possible. The prospects of relatively cheaper cancer drugs could then be brighter, particularly for the socio-economically feebler cancer patients of the world.

The Role of Reactive Oxygen Species in Tumor Treatment and its Impact on Bone Marrow Hematopoiesis

Reactive oxygen species (ROS), an important molecule inducing oxidative stress in organisms, play a key role in tumorigenesis, tumor progression and recurrence. Recent findings on ROS have shown that ROS can be used to treat cancer as they accelerate the death of tumor cells. At present, pro-oxidant drugs that are intended to increase ROS levels of the tumor cells have been widely used in the clinic. However, ROS are a double-edged sword in the treatment of tumors. High levels of ROS induce not only the death of tumor cells but also oxidative damage to normal cells, especially bone marrow hemopoietic cells, which leads to bone marrow suppression and (or) other side effects, weak efficacy of tumor treatment and even threatening patients' life. How to enhance the killing effect of ROS on tumor cells while avoiding oxidative damage to the normal cells has become an urgent issue. This study is a review of the latest progress in the role of ROS-mediated programmed death in tumor treatment and prevention and treatment of oxidative damage in bone marrow induced by ROS.

Preclinical Development of Mahanine-Enriched Fraction from Indian Spice Murraya koenigii for the Management of Cancer: Efficacy, Temperature/pH stability, Pharmacokinetics, Acute and Chronic Toxicity (14-180 Days) Studies

Murraya koenigii is well documented in the Indian ancient medical text “Charaka Samhita.” The carbazole alkaloid “mahanine” from this plant exhibited anticancer activity against several cancers. Here, we have taken a comprehensive study to standardize the method for the preparation of a mahanine-enriched fraction (MEF) with the highest yield and defined markers. Our optimized method produced MEF having the highest amount of mahanine, a major marker, with excellent in vitro antiproliferative activity against ovarian and breast cancer cells as evidenced by decreased cell viability by MTT assay. Moreover, it exhibited condensed and fragmented nuclei by DAPI staining and increased annexin V-/PI-stained cells after MEF treatment, indicating apoptosis. It also exhibited good efficacy in ovarian and breast cancer syngeneic mice models, with an ED50 of 300 mg/kg body weight (BW). MEF is stable up to 40°C for ≥3 months. Its biological activity remains unchanged at a wide range of pH (1-10) for up to ~3 hours, indicating a safe oral route of administration. Additionally, the comparative pharmacokinetics of MEF and mahanine in rats showed a 31% higher bioavailability of mahanine in MEF-fed rats compared to rats fed with mahanine alone. Furthermore, mice fed with MEF at 5000 mg/kg BW single dose, 300-1500 mg/kg BW/day for 14 days, and 300 mg/kg BW/day for 28, 90, and 180 days for subacute, subchronic, chronic studies, respectively, did not show any significant clinical signs of toxicity, behavioral changes, mortality, organ weights, serum biochemistry, and hematological parameters indicating no/minimum toxicity for up to 180 days. To the best of our knowledge, this is the first report showing the pH/temperature stability and chronic toxicity studies of MEF along with in vivo efficacy against breast cancer. Taken together, our study will enhance the commercial value of this highly potential medicinal plant and will be helpful as a reference material for its clinical development.

Medicinal Profile, Phytochemistry, and Pharmacological Activities of Murraya koenigii and its Primary Bioactive Compounds

The discovery of several revitalizing molecules that can stop or reduce the pathology of a wide range of diseases will be considered a major breakthrough of the present time. Available synthetic compounds may provoke side effects and health issues, which heightens the need for molecules from plants and other natural resources under discovery as potential methods of replacing synthetic compounds. In traditional medicinal therapies, several plant extracts and phytochemicals have been reported to impart remedial effects as better alternatives. Murraya koenigii (M. koenigii) belongs to the Rutaceae family, which is commonly used as a medicinally important herb of Indian origin in the Ayurvedic system of medicine. Previous reports have demonstrated that the leaves, roots, and bark of this plant are rich sources of carbazole alkaloids, which produce potent biological activities and pharmacological effects. These include antioxidant, antidiabetic, anti-inflammatory, antitumor, and neuroprotective activities. The present review provides insight into the major components of M. koenigii and their pharmacological activities against different pathological conditions. The review also emphasizes the need for more research on the molecular basis of such activity in various cellular and animal models to validate the efficacy of M. koenigii and its derivatives as potent therapeutic agents.

PFKFB3 inhibition reprograms malignant pleural mesothelioma to nutrient stress-induced macropinocytosis and ER stress as independent binary adaptive responses

The metabolic signatures of cancer cells are often associated with elevated glycolysis. Pharmacological (PFK158 treatment) and genetic inhibition of 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3), a critical control point in the glycolytic pathway, decreases glucose uptake, ATP production, and lactate dehydrogenase activity and arrests malignant pleural mesothelioma (MPM) cells in the G0/G1 phase to induce cell death. To overcome this nutrient stress, inhibition of PFKFB3 activity led to an escalation in endoplasmic reticulum (ER) activity and aggravated ER stress mostly by upregulating BiP and GADD153 expression and activation of the endocytic Rac1-Rab5-Rab7 pathway resulting in a unique form of cell death called “methuosis” in both the sarcomatoid (H28) and epithelioid (EMMeso) cells. Transmission electron microscopy (TEM) analysis showed the formation of nascent macropinocytotic vesicles, which rapidly coalesced to form large vacuoles with compromised lysosomal function. Both immunofluorescence microscopy and co-immunoprecipitation analyses revealed that upon PFKFB3 inhibition, two crucial biomolecules of each pathway, Rac1 and Calnexin interact with each other. Finally, PFK158 alone and in combination with carboplatin-inhibited tumorigenesis of EMMeso xenografts in vivo. Since most cancer cells exhibit an increased glycolytic rate, these results provide evidence for PFK158, in combination with standard chemotherapy, may have a potential in the treatment of MPM.

Carbazole scaffolds in cancer therapy: a review from 2012 to 2018

For over half a century, the carbazole skeleton has been the key structural motif of many biologically active compounds including natural and synthetic products. Carbazoles have taken an important part in all the existing anti-cancer drugs because of their discovery from a large variety of organisms, including bacteria, fungi, plants, and animals. In this article, we specifically explored the literature from 2012 to 2018 on the anti-tumour activities reported to carbazole derivatives and we have critically collected the most significant data. The most described carbazole anti-tumour agents were classified according to their structure, starting from the tricyclic–carbazole motif to fused tetra-, penta-, hexa- and heptacyclic carbazoles. To date, three derivatives are available on the market and approved in cancer therapy.

Mahanine, A dietary phytochemical, represses mammary tumor burden in rat and inhibits subtype regardless breast cancer progression through suppressing self-renewal of breast cancer stem cells

Mahanine (MH), a carbazole alkaloid isolated from an edible plant (Murraya koenigii), potentially inhibits the growth of altered subtypes of breast cancer cells in vitro and significantly reduced the mammary tumor burden in N-Methyl-N-nitrosourea (MNU) induced rat. The experimental results showed that 20-25 μM of MH for 24 h of treatment was very potent to reduce the cell proliferation through apoptosis with arresting the cells in G₀/G₁ in both ER⁺/p53^WT MCF-7 and triple negative/p53^Mut MDA-MB-231 cells. On the other hand, 10-15 μM of MH exposure to those two cell lines, caused inhibition of mammosphere formation and reduction of CD44^high/CD24^low/epithelial-specific antigen-positive (ESA+) population, which ultimately led to loss of self-renewal ability of breast cancer stem cells. Further, in vivo observation indicated that intraperitoneal injection of MH for four weeks with a dose of 50 mg/kg body weight thrice in a week, significantly (P =  0.03) reduced the mammary tumor weight in MNU induced rat. In conclusion, this study provides the novel insight into the mechanism of MH mediated growth arrest in subtype irrespective breast cancer progression.

Ochratoxin A Exposure Impairs Porcine Granulosa Cell Growth via the PI3K/AKT Signaling Pathway

The mycotoxin ochratoxin A (OTA), a naturally occurring food contaminant, has a toxic effect on the growth and development of follicles in pigs. However, little is known regarding the specific toxic effects of OTA exposure on oocytes and granulosa cells (GCs). In this study, we cultured porcine ovarian GCs and exposed them to OTA in vitro in order to explore the mechanism causing the negative effects. Initially, it was found that OTA exposure inhibited cell viability in a time and dose dependent manner. We also showed that OTA exposure increased oxidative stress, decreased proliferation ratio, and increased apoptosis ratio in GCs. We revealed an important role for the PI3K/AKT signal pathway in GC proliferation and apoptosis by RNA-seq analysis. The results not only showed that OTA treatment significantly affected the expression of genes within the PI3K/AKT pathway but also demonstrated a concrete relationship between the PI3K/AKT pathway and GC cell proliferation and apoptosis. In conclusion, the results demonstrated that OTA exposure impaired porcine GC growth via the PI3K/AKT signaling pathway.

Genipin Enhances the Therapeutic Effects of Oxaliplatin by Upregulating BIM in Colorectal Cancer

Despite an increase in the survival rate of patients with cancer owing to the use of current chemotherapeutic agents, adverse effects of cancer therapies remain a concern. Combination therapies have been developed to increase efficacy, reduce adverse effects, and overcome drug resistance. Genipin is a natural product derived from Gardenia jasminoides, which has been associated with anti-inflammatory, anti-angiogenic, and anti-proliferative effects; hypertension; and anti-ischemic brain injuries. However, the enhancement of oxaliplatin sensitivity by genipin remains unexplored. Our study showed that a combination of genipin and oxaliplatin exerts synergistic antitumor effects in vitro and in vivo in colorectal cancer cell lines through the reactive oxygen species (ROS)/endoplasmic reticulum (ER) stress/BIM pathway. Importantly, the combination did not affect normal colon cells. BIM knockdown markedly inhibited apoptosis induced by the combination. In addition, genipin induced ROS by inhibiting superoxide dismutase 3 activity. These findings suggest that genipin may be a novel agent for increasing the sensitivity of oxaliplatin against colorectal cancer. The combination of oxaliplatin and genipin hold significant therapeutic potential with minimal adverse effects.

Mahanimbine Exerts Anticancer Effects on Human Pancreatic Cancer Cells by Triggering Cell Cycle Arrest, Apoptosis, and Modulation of AKT/Mammalian Target of Rapamycin (mTOR) and Signal Transducer and Activator of Transcription 3 (STAT3) Signalling Pathways

Background

Pancreatic cancer causes tremendous mortality across the globe mainly due to late diagnosis and unavailability of efficient chemotheruptic agents. In the current study the anticancer potential of a plant derived alkaloid, Mahanimbine, was examined against a panel of pancreatic cancer cells.

Material/Methods

The cell proliferation was determined by MTT assay. Annexin V/PI and DAPI staining were performed to detect apoptosis. Cell cycle distribution was investigated by flow cytometery. Cell migration was detected by wound healing assay and protein expression was checked by western blotting.

Results

The results revealed that Mahanimbine could inhibit the proliferation of the all the pancreatic cancer cells with lower cytoxicity against the normal cells. The IC₅₀ ranged from 3.5 to 64 μM against the pancreatic cancer cell lines. The lowest IC₅₀ of 3.5 μM was observed tor the Capan-2 and SW119 pancreatic cancer cell lines. The anticancer activity of Mahanimbine against the Capan-2 and SW119 cells was found to be due to G₀/G₁ cell cycle arrest and induction of apoptosis. Mahanimbine prompted apoptosis was also associated with decline in Bcl-2 and enhancement of the Bax expression. Further, it was observed that Mahanimbine could inhibit the AKT/mTOR and STAT3 signalling pathways in the Capan-2 and SW119 pancreatic cancer cells. The effects of the Mahanimbine were also examined on the migration of the Capan-2 and SW119 pancreatic cancer cells. It was found that Mahanimbine could inhibit the motility and migration of both the pancreatic cancer cell lines.

Conclusions

We found that Mahanimbine inhibits the proliferation of pancreatic cancer cells and as such Mahanimbine may prove beneficial in the management of pancreatic cancer.

Autophagy-independent induction of LC3B through oxidative stress reveals its non-canonical role in anoikis of ovarian cancer cells

Cancer cells display abnormal redox metabolism. Autophagy, anoikis and reactive oxygen species (ROS) play a regulatory role during metastasis. LC3 is a well-known essential molecule for autophagy. Therefore, we wanted to explore the molecular interplay between autophagy, anoikis, and ROS in relation to LC3B. We observed enhanced LC3B level along with increased expression of p62 and modulation of other autophagy-related molecules (Atg 3, 5, 7, 12, 16L1 and Beclin1) by inducing oxidative-stress in ovarian cancer cells using a ROS-producing pro-oxidant molecule. Surprisingly, enhanced LC3B was unable to induce autophagosome formation rather promoted anoikis. ROS-induced inhibition of autophagosome-formation is possibly due to the instability of autophagy initiator, ULK1 complex. Moreover, such upregulation of LC3B via ROS enhanced several apoptotic molecules. Silencing LC3B reduced these apoptotic molecules and increased when overexpressed, suggesting its role in apoptosis. Furthermore, LC3B-dependent apoptosis was decreased by inhibiting ROS, indicating a possible link between ROS, LC3B, and apoptosis. Additionally, ROS-induced enhanced LC3B promoted detachment-induced cell death (anoikis). This was further reflected by reduced cell adhesion molecules (integrin-β3 and focal adhesion kinase) and mesenchymal markers (snail and slug). Our in vitro experimental data was further confirmed in primary tumors developed in syngeneic mice, which also showed ROS-mediated LC3B enhancement along with reduced autophagosomes, integrin-β3 and focal adhesion kinase ultimately leading to the decreased tumor mass. Additionally, primary cells from high-grade serous carcinoma patient's ascites exhibited LC3B enhancement and autophagy inhibition through ROS which provided a clinical relevance of our study. Taken together, this is the first evidence for a non-canonical role of LC3B in promoting anoikis in contrast to autophagy and may, therefore, consider as a potential therapeutic target molecule in ovarian cancer. Taken together, autophagy-inhibition may be an alternative approach to induce apoptosis/anoikis in cancer.

Porphyrin-Gold Nanomaterial for Efficient Drug Delivery to Cancerous Cells

With an aim to overcome multidrug resistance (MDR), nontargeted delivery, and drug toxicity, we developed a new nanochemotherapeutic system with tetrasodium salt of meso-tetrakis(4-sulfonatophenyl)porphyrin (TPPS) armored on gold nanoparticles (TPPS-AuNPs). The nanocarrier is able to be selectively internalized within tumor cells than in normal cells followed by endocytosis and therefore delivers the antitumor drug doxorubicin (DOX) particularly to the nucleus of diseased cells. The embedment of TPPS on the gold nanosurface provides excellent stability and biocompatibility to the nanoparticles. Porphyrin interacts with the gold nanosurface through the coordination interaction between gold and pyrrolic nitrogen atoms of the porphyrin and forms a strong association complex. DOX-loaded nanocomposite (DOX@TPPS-AuNPs) demonstrated enhanced cellular uptake with significantly reduced drug efflux in MDR brain cancer cells, thereby increasing the retention time of the drug within tumor cells. It exhibited about 9 times greater potency for cellular apoptosis via triggered release commenced by acidic pH. DOX has been successfully loaded on the porphyrin-modified gold nanosurface noncovalently with high encapsulation efficacy (∼90%) and tightly associated under normal physiological conditions but capable of releasing ∼81% of drug in a low-pH environment. Subsequently, DOX-loaded TPPS-AuNPs exhibited higher inhibition of cellular metastasis, invasion, and angiogenesis, suggesting that TPPS-modified AuNPs could improve the therapeutic efficacy of the drug molecule. Unlike free DOX, drug-loaded TPPS-AuNPs did not show toxicity toward normal cells. Therefore, higher drug encapsulation efficacy with selective targeting potential and acidic-pH-mediated intracellular release of DOX at the nucleus make TPPS-AuNPs a "magic bullet" for implication in nanomedicine.

Mahanine drives pancreatic adenocarcinoma cells into endoplasmic reticular stress-mediated apoptosis through modulating sialylation process and Ca2+-signaling

Endoplasmic reticulum (ER) stress results from protein unfolding/misfolding during cellular maturation, which requires a coordinated action of several chaperones and enzymes and Ca²⁺ signalling. ER-stress possibly has a positive effect on survival of pancreatic cancer cell. Therefore, detailed insights into this complex signaling network are urgently needed. Here, we systematically analyzed the impact of ER stress-mediated unfolded protein response (UPR) and Ca²⁺-signaling cross-talk for the survival of pancreatic adenocarcinoma (PDAC) cells. We observed enhanced ER activity and initiation of UPR signaling induced by a carbazole alkaloid (mahanine). This event triggers a time-dependent increase of intracellular Ca²⁺ leakage from ER and subsequently Ca²⁺ signaling induced by enhanced reactive oxygen species (ROS) produced by this pro-oxidant agent. In addition, we observed an altered glycosylation, in particular with regard to reduced linkage-specific sialic acids possibly due to decreased sialyltransferase activity. Changes in sialylation entailed enhanced expression of the ganglioside GD3 in the treated cells. GD3, an inducer of apoptosis, inhibited pancreatic xenograft tumor. Taken together, our study describes a molecular scenario how PDAC cells are driven into apoptosis by mahanine by UPR-driven ER stress-associated and ROS-mediated calcium signaling and possibly defective sialylation.

Structure-Based Kinase Profiling To Understand the Polypharmacological Behavior of Therapeutic Molecules

Several drugs elicit their therapeutic efficacy by modulating multiple cellular targets and possess varied polypharmacological actions. The identification of the molecular targets of a potent bioactive molecule is essential in determining its overall polypharmacological profile. Experimental procedures are expensive and time-consuming. Therefore, computational approaches are actively implemented in rational drug discovery. Here, we demonstrate a computational pipeline, based on reverse virtual screening technique using several consensus scoring strategies, and perform structure-based kinase profiling of 12 FDA-approved drugs. This target prediction showed an overall good performance, with an average AU-ROC greater than 0.85 for most drugs, and identified the true targets even at the top 2% cutoff. In contrast, 10 non-kinase binder drugs exhibited lower binding efficiency and appeared in the bottom of ranking list. Subsequently, we validated this pipeline on a potent therapeutic molecule, mahanine, whose polypharmacological profile related to targeting kinases is unknown. Our target-prediction method identified different kinases. Furthermore, we have experimentally validated that mahanine is able to modulate multiple kinases that are involved in cross-talk with different signaling molecules, which thereby exhibits its polypharmacological action. More importantly, in vitro kinase assay exhibited the inhibitory effect of mahanine on two such predicted kinases' (mTOR and VEGFR2) activity, with IC₅₀ values being ∼12 and ∼22 μM, respectively. Next, we generated a comprehensive drug-protein interaction fingerprint that explained the basis of their target selectivity. We observed that it is controlled by variations in kinase conformations followed by significant differences in crucial hydrogen-bond and van der Waals interactions. Such structure-based kinase profiling could provide useful information in revealing the unknown targets of therapeutic molecules from their polypharmacological behavior and would assist in drug discovery.

mTORC2 regulates hedgehog pathway activity by promoting stability to Gli2 protein and its nuclear translocation

mTORC2 is aberrantly activated in cancer and therefore is considered to be an important therapeutic target. The hedgehog pathway, which is also often hyperactivated, regulates transcription of several genes associated with angiogenesis, metastasis, cellular proliferation and cancer stem cell (CSC) regeneration. However, the contribution of mTORC2 toward hedgehog pathway activity has not been explored yet. Here we have addressed the molecular cross talk between mTORC2 and hedgehog pathway activities in the context of glioblastoma multiforme, a malignant brain tumor using as a model system. We observed that higher mTORC2 activity enhanced the expression of a few hedgehog pathway molecules (Gli1, Gli2 and Ptch1) and amplified its target genes (Cyclin D1, Cyclin D2, Cyclin E, Snail, Slug and VEGF) both in mRNA and protein levels as corroborated by increased metastasis, angiogenesis, cellular proliferation and stem cell regeneration. Inhibition of mTORC2 formation decreased hedgehog pathway activity and attenuated all these above-mentioned events, suggesting their cross talk with each other. Further investigations revealed that mTORC2 inhibited ubiquitination of Gli2 by inactivating GSK3β, and thus it promotes stability to Gli2 and its nuclear translocation. Moreover, enhanced mTORC2 activity led to the increased clonogenic properties and CD133+ cells, indicating its role in CSC regeneration. mTORC2 inhibitor directed the reduction of hedgehog pathway proteins and also reduced CSCs. Thus, our observations support a role for elevated mTORC2 activity in regulating angiogenesis, metastasis, cellular proliferation and CSC regeneration via hedgehog pathway activity. Taken together, it provides a rationale for including the mTOR2 inhibitor as part of the therapeutic regimen for CSCs.

Mahanine exerts in vitro and in vivo antileishmanial activity by modulation of redox homeostasis

Earlier we have established a carbazole alkaloid (mahanine) isolated from an Indian edible medicinal plant as an anticancer agent with minimal effect on normal cells. Here we report for the first time that mahanine-treated drug resistant and sensitive virulent Leishmania donovani promastigotes underwent apoptosis through phosphatidylserine externalization, DNA fragmentation and cell cycle arrest. An early induction of reactive oxygen species (ROS) suggests that the mahanine-induced apoptosis was mediated by oxidative stress. Additionally, mahanine-treated Leishmania-infected macrophages exhibited anti-amastigote activity by nitric oxide (NO)/ROS generation along with suppression of uncoupling protein 2 and Th1-biased cytokines response through modulating STAT pathway. Moreover, we have demonstrated the interaction of a few antioxidant enzymes present in parasite with mahanine through molecular modeling. Reduced genetic and protein level expression of one such enzyme namely ascorbate peroxidase was also observed in mahanine-treated promastigotes. Furthermore, oral administration of mahanine in acute murine model exhibited almost complete reduction of parasite burden, upregulation of NO/iNOS/ROS/IL-12 and T cell proliferation. Taken together, we have established a new function of mahanine as a potent antileishmanial molecule, capable of inducing ROS and exploit antioxidant enzymes in parasite along with modulation of host's immune response which could be developed as an inexpensive and nontoxic therapeutics either alone or in combination.

Isomahanine induces endoplasmic reticulum stress and simultaneously triggers p38 MAPK-mediated apoptosis and autophagy in multidrug-resistant human oral squamous cell carcinoma cells

Advanced oral squamous cell carcinoma (OSCC) is typically aggressive and closely correlated with disease recurrence and poor survival. Multidrug resistance (MDR) is the most critical problem leading to therapeutic failure. Investigation of novel anticancer candidates targeting multidrug-resistant OSCC cells may provide a basis for developing effective strategies for OSCC treatment. In the present study, we investigated the cytotoxic mechanism of a carbazole alkaloid, namely isomahanine, in a multidrug‑resistant OSCC cell line CLS-354/DX. We demonstrated that CLS-354/DX cells overexpressing multidrug resistance-associated protein 1 (MRP1) were resistant to anticancer drugs cisplatin and camptothecin. Isomahanine effectively induced cytotoxicity against CLS-354/DX cells regardless of resistance. Apoptosis as determined by FITC‑Annexin V/PI staining and western blot analysis of cleaved caspase-3 and cleaved poly(ADP‑ribose) polymerase (PARP) was significantly induced in a time-dependent manner upon isomahanine treatment. Isomahanine-induced caspase‑dependent apoptosis was determined using z-VAD‑fmk. The effects on autophagy in isomahanine-treated cells were investigated via conversion of LC3B and degradation of p62/SQSTM1 (p62). Isomahanine obviously induced autophagic flux as shown by an increase in punctate GFP-LC3B and the LC3B-II/LC3B-I ratio with a concomitant decrease in p62 levels. Autophagy inhibitors 3-methyladenine (3-MA) and chloroquine (CQ) protected isomahanine-induced cell death, indicating the activation of autophagic cell death. Endoplasmic reticulum (ER) stress and MAPK activation were examined to elucidate the mechanism underlying cell death. The expression levels of PERK, CHOP and phosphorylated MAPK (p38, ERK1/2 and JNK1/2) were upregulated following isomahanine treatment. We found that p38 MAPK inhibitor (SB203580) significantly attenuated isomahanine-induced apoptosis and autophagic flux and this prevented cell death. Collectively, the present study demonstrated that isomahanine was able to induce ER stress and trigger p38 MAPK-mediated apoptosis and autophagic cell death in multidrug-resistant OSCC cells. The potential cytotoxic action of isomahanine may provide the development of anticancer candidates for treating multidrug-resistant cancer.

Hydrogen Sulfide and/or Ammonia Reduces Spermatozoa Motility through AMPK/AKT Related Pathways

A number of emerging studies suggest that air pollutants such as hydrogen sulfide (H₂S) and ammonia (NH₃) may cause a decline in spermatozoa motility. The impact and underlying mechanisms are currently unknown. Boar spermatozoa (in vitro) and peripubertal male mice (in vivo) were exposed to H₂S and/or NH₃ to evaluate the impact on spermatozoa motility. Na₂S and/or NH₄Cl reduced the motility of boar spermatozoa in vitro. Na₂S and/or NH₄Cl disrupted multiple signaling pathways including decreasing Na⁺/K⁺ ATPase activity and protein kinase B (AKT) levels, activating Adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) and phosphatase and tensin homolog deleted on chromosome ten (PTEN), and increasing reactive oxygen species (ROS) to diminish boar spermatozoa motility. The increase in ROS might have activated PTEN, which in turn diminished AKT activation. The ATP deficiency (indicated by reduction in Na⁺/K⁺ ATPase activity), transforming growth factor (TGF_β) activated kinase-1 (TAK1) activation, and AKT deactivation stimulated AMPK, which caused a decline in boar spermatozoa motility. Simultaneously, the deactivation of AKT might play some role in the reduction of boar spermatozoa motility. Furthermore, Na₂S and/or NH₄Cl declined the motility of mouse spermatozoa without affecting mouse body weight gain in vivo. Findings of the present study suggest that H₂S and/or NH₃ are adversely associated with spermatozoa motility.

Synergistic anticancer effect of exogenous wild-type p53 gene combined with 5-FU in human colon cancer resistant to 5-FU in vivo

AIM

To investigate the anticancer effect of a recombinant adenovirus-mediated p53 (rAd-p53) combined with 5-fluorouracil (5-FU) in human colon cancer resistant to 5-FU in vivo and the mechanism of rAd-p53 in reversal of 5-FU resistance.

METHODS

Nude mice bearing human colon cancer SW480/5-FU (5-FU resistant) were randomly assigned to four groups (n = 25 each): control group, 5-FU group, rAd-p53 group, and rAd-p53 + 5-FU group. At 24 h, 48 h, 72 h, 120 h and 168 h after treatment, 5 mice were randomly selected from each group and sacrificed using an overdose of anesthetics. The tumors were removed and the protein expressions of p53, protein kinase C (PKC), permeability-glycoprotein (P-gp) and multidrug resistance-associated protein 1 (MRP1) (Western blot) and apoptosis (TUNEL) were determined.

RESULTS

The area ratios of tumor cell apoptosis were larger in the rAd/p53 + 5-FU group than that in the control, 5-FU and rAd/p53 groups (P < 0.05), and were larger in the rAd/p53 group than that of the control group (P < 0.05) and the 5-FU group at more than 48 h (P < 0.05). The p53 expression was higher in the rAd/p53 and the rAd/p53 + 5-FU groups than that of the control and 5-FU groups (P < 0.05), and were higher in the rAd/p53 + 5-FU group than that of the rAd/p53 group (P < 0.05). Overexpression of PKC, P-gp and MRP1 was observed in the 5-FU and control groups. In the rAd/p53 + 5-FU group, the expression of P-gp and MRP1 was lower that of the control and 5-FU groups (P < 0.05), and the expression of PKC was lower than that of the control, 5-FU and rAd/p53 groups at more than 48 h (P < 0.05). In the rAd/p53 group, the expression of P-gp and MRP1 was lower that of the control and 5-FU groups at more than 48 h (P < 0.05), and the expression of PKC was lower than that of the control and 5-FU groups at more than 120 h (P < 0.05).

CONCLUSION

5-FU combined with rAd-p53 has a synergistic anticancer effect in SW480/5-FU (5-FU resistance), which contributes to reversal of 5-FU resistance.

PTEN negatively regulates mTORC2 formation and signaling in grade IV glioma via Rictor hyperphosphorylation at Thr1135 and direct the mode of action of an mTORC1/2 inhibitor

To investigate the role of PTEN (phosphatase and tensin homolog) in mammalian target of rapamycin complex 2 (mTORC2) signaling in glioblastoma multiforme (GBM), we found higher activation of mTORC2 in PTEN(mu) cells, as evidenced by enhanced phosphorylation of mTOR (Ser2481), AKT (Ser473) and glycogen synthase kinase 3 beta (GSK3β) (Ser9) as compared with PTEN(wt) cells. In addition, PTEN(wt) cells upon PTEN depletion showed mTORC2 activation. The reduced mTORC2 signaling in PTEN(wt) cells was related to higher Rictor phosphorylation at Thr1135 residue. Phosphorylation of Rictor at Thr1135 inhibited its association with mTORC and thus there was a reduction in mTORC2 complex formation. In addition, PTEN(wt) cells expressing mutated Rictor in which Thr1135 was substituted with alanine, showed enhanced mTORC2 formation and signaling. This enhanced mTORC2 signaling promoted inactivation of GSK3β. Thus, we established the reciprocal activation of mTORC2 and GSK3β in GBM. To the best of our knowledge, this is the first report describing role of PTEN in mTORC2 formation by promoting Rictor phosphorylation (Thr1135) in GBM. Furthermore, the drug sensitivity of mTORC2 was evaluated. A newly identified carbazole alkaloid, mahanine, showed cytotoxicity in both PTEN(mu) and PTEN(wt) cells. It inhibited both mTORC1/2 and AKT completely in PTEN(mu) cells, whereas it inhibited only mTORC1 in PTEN(wt) cells. Cytotoxity and AKT-inhibitory activity of the mTORC1/2 inhibitor was increased either by depleting PTEN or in combination with phosphatidylinositol 3 kinase inhibitors in PTEN(wt) cells. In contrast, depletion of Rictor decreased the cytotoxicity of the mTORC1/2 inhibitor in PTEN(mu) cells. Thus, PTEN has an important role in mTORC2 formation and also influences the effectiveness of an mTORC1/2 inhibitor in GBM.

JNK suppression of chemotherapeutic agents-induced ROS confers chemoresistance on pancreatic cancer stem cells

Chemoresistance associated with cancer stem cells (CSCs), which is now being held responsible for the pervasive therapy resistance of pancreatic cancer, poses a major challenge to the successful management of this devastating malignancy. However, the molecular mechanism underlying the marked chemoresistance of pancreatic CSCs remains largely unknown. Here we show that JNK, which is upregulated in pancreatic CSCs and contributes to their maintenance, is critically involved in the resistance of pancreatic CSCs to 5-fluorouracil (5-FU) and gemcitabine (GEM). We found that JNK inhibition effectively sensitizes otherwise chemoresistant pancreatic CSCs to 5-FU and GEM. Significantly, JNK inhibition promoted 5-FU- and GEM-induced increase in intracellular reactive oxygen species (ROS), and scavenging intracellular ROS by use of N-acetylcysteine impaired JNK inhibition-mediated promotion of the cytotoxicity of 5-FU and GEM. Our findings thus suggest that JNK may contribute to the chemoresistance of pancreatic CSCs through prevention of chemotherapeutic agents-induced increase in intracellular ROS. Our findings also suggest that JNK inhibition combined with 5-FU- and/or GEM-based regimens may be a rational therapeutic approach to effectively eliminate pancreatic CSCs.

β-Cryptoxanthin Synergistically Enhances the Antitumoral Activity of Oxaliplatin through ΔNP73 Negative Regulation in Colon Cancer

BACKGROUND

The acquired resistance to chemotherapy represents the major limitation in the treatment of cancer. New strategies to solve this failure and improve patients' outcomes are necessary. The cancer preventive effect of β-cryptoxanthin has been widely described in population studies. Few reports support its putative use as an antitumoral compound. Here we focus on the therapeutic potential of β-cryptoxanthin individually or in combination with oxaliplatin in colon cancer and try to decipher the molecular basis underlying its effect.

METHODS

Apoptosis, viability and proliferation assays, mouse models, and an intervention study in 20 healthy subjects were performed. A PCR array was carried out to unravel the molecular putative basis of the β-cryptoxanthin effect, and further signaling experiments were conducted. Comet Assay was completed to evaluate the genotoxicity of the treatments.

RESULTS

β-Cryptoxanthin differentially regulates the expression of the P73 variants in vitro, in vivo, and in a human intervention study. This carotenoid decreases the proliferation of cancer cells and cooperates with oxaliplatin to induce apoptosis through the negative regulation of ΔNP73. The antitumoral concentrations of oxaliplatin decrease in the presence of β-cryptoxanthin to achieve same percentage of growth inhibition. The genotoxicity in peripheral blood mononuclear cells of mice decreased in the combined treatment.

CONCLUSIONS

We propose a putative novel therapeutic strategy for the treatment of colon cancer based on the combination of β-cryptoxanthin and oxaliplatin. The combined regimen produced more benefit than either individual modality without increasing side effects. In addition, the concentration-limiting toxicity of oxaliplatin is reduced in the presence of the carotenoid.

A balancing act: orchestrating amino-truncated and full-length p73 variants as decisive factors in cancer progression

p73 is the older sibling of p53 and mimics most of its tumor-suppressor functions. Through alternative promoter usage and splicing, the TP73 gene generates more than two dozen isoforms of which N-terminal truncated DNp73 variants have a decisive role in cancer pathogenesis as they outweigh the positive effects of full-length TAp73 and p53 in acting as a barrier to tumor development. Beyond the prevailing view that DNp73 predominantly counteract cell cycle arrest and apoptosis, latest progress indicates that these isoforms acquire novel functions in epithelial-to-mesenchymal transition, metastasis and therapy resistance. New insight into the mechanisms underlying this behavior reinforced the expectation that DNp73 variants contribute to aggressive cellular traits through both loss of wild-type tumor-suppressor activity and gain-of-function, suggesting an equally important role in cancer progression as mutant p53. In this review, we describe the novel properties of DNp73 in the invasion metastasis cascade and outline the comprehensive p73 regulatome with an emphasis on molecular processes putting TAp73 out of action in advanced tumors. These intriguing insights provoke a new understanding of the acquisition of aggressive traits by cancer cells and may help to set novel therapies for a broad range of metastatic tumors.

Fish oil suppresses cell growth and metastatic potential by regulating PTEN and NF-κB signaling in colorectal cancer

Homeostasis in eukaryotic tissues is tightly regulated by an intricate balance of the prosurvival and antisurvival signals. The tumor suppressor PTEN (phosphatase and tensin homolog deleted on chromosome 10), a dual-specificity phosphatase, plays a functional role in cell cycle arrest and apoptosis. NF-κB and its downstream regulators (such as VEGF) play a central role in prevention of apoptosis, promotion of inflammation and tumor growth. Therefore, we thought to estimate the expression of PTEN, Poly-ADP-ribose polymerase (PARP), NF-κBp50, NF-κBp65 and VEGF to evaluate the effect of supplementation of fish oil on apoptotic and inflammatory signaling in colon carcinoma. Male wistar rats in Group I received purified diet while Group II and III received modified diet supplemented with FO∶CO(1∶1)&FO∶CO(2.5∶1) respectively. These were further subdivided into controls receiving ethylenediamine-tetra acetic-acid and treated groups received dimethylhydrazine-dihydrochloride (DMH)/week for 4 weeks. Animals sacrificed 48 hours after last injection constituted initiation phase and that sacrificed after 16 weeks constituted post-initiation phase. We have analysed expression of PTEN, NF-κBp50, NF-κBp65 by flowcytometer and nuclear localization of NF-κB by immunofluorescence. PARP and VEGF were assessed by immunohistochemistry. In the initiation phase, animals receiving DMH have shown increased % of apoptotic cells, PTEN, PARP, NF-κBp50, NF-κBp65 and VEGF however in post-initiation phase no significant alteration in apoptosis with decreased PTEN and increased PARP, NF-κBp50, NF-κBp65 and VEGF were observed as compared to control animals. On treatment with both ratios of fish oil in both the phases, augmentation in % of apoptotic cells, decreased PTEN, PARP, NF-κBp50, NF-κBp65 and VEGF were documented with respect to DMH treated animals with effect being more exerted with higher ration in post-initiation phase. Hence, fish oil activates apoptosis, diminishes DNA damage and inhibits inflammatory signalling in a dose and time dependent manner so as to inhibit progression of colon cancer.